The fire was nearly under control shortly after 10 p.m., but flames reignited on another building nearby.

“(Firefighters) had difficulty reaching the site because of the narrow alleys, and the high temperature caused by an explosion, causing the operation to be prolonged,” said Park Chi-hak from Jongno Fire Station.

More than 170 firefighters and some 50 fire engines were dispatched to the site, according to the officials from the rescue service.

Six buildings, with 23 stores, caught fire and seven people at the site have been taken to hospital after inhaling smoke from the fire. Other residents and visitors in the area were evacuated shortly after the fire broke out.

Police said there were no deaths reported yet, but added that the site would be further investigated to track down any additional damage.

The district where the fire broke out was an alley full of small restaurants in wood-framed buildings that are susceptible to fire. The blaze grew after liquefied petroleum gas used in one of the restaurants exploded.

Police suspect that gas tubes or transformers were the cause of the fire but the exact cause has yet to be identified. Four burnt out gas tubes and three transformers were found at the site, according to police.